Lord Coe was right to pull out of the race to become chairman of the BBC Trust because the role is so "ill-defined," a former senior boss at the corporation has said.

Roger Mosey, who ran the BBC's coverage of the 2012 Olympics and is a former head of TV News, took to Twitter to praise Lord Coe's announcement that he was no longer in the running for the role.

Mr Mosey said that Lord Coe, who chaired the organising committee of the London 2012 Olympics, was "a terrific character" who should not "risk" taking up the role at the Trust, the governing body of the BBC that has been described as "broken" by MPs.

The former TV executive, who is now Master of Selwyn College, Cambridge, tweeted: "Correct call by Seb Coe not to go for BBC Trust Chairman. He's a terrific character, so best not to risk that in such an ill-defined role."

Lord Coe, a former Olympic gold medal-winning middle distance runner, said earlier on Tuesday that he was no longer in the running to replace former chairman Lord Pattern, who unexpectedly resigned in May because of ill-health.

The ex-athlete said he did not have the "capacity" for the role, adding: "I did allow my name to go forward to give myself time to properly analyse whether I had enough time to do the job to the best of my abilities."

Earlier this year, Mr Mosey called on the next chair of the BBC Trust to abolish the role, saying the Trust hadn't worked "as a regulatory body".

He called for much of the red tape associated with the Trust to be abolished, and for the chairman to sit "unmistakably" within the BBC building.

The BBC Trust was set up by the 2007 Royal Charter for the BBC to set "the overall strategic direction of the BBC" and to oversee its executive board, which is chaired by the director-general.

But Lord Pattern, a former Conservative cabinet minister, and the Trust faced criticism, from the National Audit Office and the House of Commons Public Accounts Committee among others, for allowing the executive board to agree to pay £25m to 150 outgoing senior executives who took redundancy between 2009 and 2012.

Critics say that the role of the Trust - which is both part of the BBC and its regulator - is confused that the Trust should be scrapped when the corporation's charter is renewed next year.

The scandal broke in the summer of last year, months after George Entwistle resigned as director-general of the BBC after 54 days over the Jimmy Savile scandal.